Consider the following :
I. Methane digester
II. Biodiesel
III. Natural compost
How many of the above are examples of clean technologies?

Clean technology (cleantech) refers to any process, product, or service that reduces negative environmental impacts through significant energy efficiency improvements, the sustainable use of resources, or environmental protection activities.

• Methane digesters (anaerobic digesters) are clean technologies that break down organic waste to produce biogas, a renewable energy source, while reducing greenhouse gas emissions from landfills.
• Biodiesel is a renewable, biodegradable fuel derived from vegetable oils or animal fats. It serves as a cleaner alternative to petroleum diesel, significantly reducing carbon emissions.
• Natural compost is a sustainable waste management technology that recycles organic matter into nutrient-rich soil. It reduces the need for chemical fertilizers and prevents methane release from anaerobic decomposition in landfills.

As all three promote environmental sustainability and resource efficiency, they are all classified as clean technologies.